1. Field of the Invention
The present invention relates to a speaker system in a display, and more particularly, to a speaker system in a display, in which a structure of the speaker system is changed to a duct change type, for easy phase inversion of a particular frequency of sound generated from a back surface of a speaker.
2. Background of the Related Art
A related art speaker system in a display and operation thereof will be explained with reference to FIG. 1.
Referring to FIG. 1, the related art speaker system of a track type is provided with a track type speaker 1 (hereafter called as xe2x80x9cspeakerxe2x80x9d), and a rear sound box 2 in rear of the speaker 1. The speaker has a frame 102, a gasket 103 inside of the frame 102, an edge 104 fitted to form a ring on an inside of the gasket 103, a cone paper 105 attached to an inside of the edge 104 in a form of a cone. There is a duct 3a in the rear sound box 2 as a unit therewith for inverting a phase of the sound generated from a back surface of the speaker 1. There is a cylindrical speaker system mount 106 on a top of the speaker 1 for coupling the speaker system to a speaker system fastening boss 5 fixed on a cabinet(not shown) of the display, and the speaker system mount 106 has anti-vibration rubber 6 for preventing a vibration transmitted from the speaker system to the cabinet.
The operation of the foregoing related art speaker system will be explained.
When the speaker system is in operation, there is a sound (xe2x80x9cAxe2x80x9d in the drawing) of a certain frequency band is generated in a front surface of the speaker 1. And, there is another sound (xe2x80x9c-Axe2x80x9d in the drawing) having the same frequency with, but having a phase opposite to the sound xe2x80x9cAxe2x80x9d is generated in the back surface of the speaker 1. Therefore, it is required to invert the phase of the sound xe2x80x9c-Axe2x80x9d generated in the back surface of the speaker 1. The phase inversion is done as the sound xe2x80x9c-Axe2x80x9d generated in a back surface of the speaker 1 passes through the duct 3a, but for only a portion of the sound (xe2x80x9c-Axe2x80x9d) with a particular frequency. The sound with a particular frequency from the duct 3a having an inverted phase(represented as xe2x80x9cBxe2x80x9d in the drawing) reinforces the sound xe2x80x9cBxe2x80x9d with an identical frequency among the sound xe2x80x9cAxe2x80x9d from the front surface of the speaker 1, thereby providing a low sound reinforcing effect. The frequency xe2x80x9cfxe2x80x9d of the sound from the duct 3a can be expressed with an equation, below.   f  =            1              2        ⁢                  xe2x80x83                ⁢        π              ⁢                  Sc        Mp            
Where, Mp denotes mass of air in the duct, which is a function of a length and a sectional area of the duct, and Sc denotes a stiffness of the sound box, which is a function of an internal volume. Therefore, if dimensions of the rear sound box are fixed, that is the internal volume Sc is constant, the frequency of the sound from the duct 3a is fixed depending on the length and sectional area of the duct.
However, the formation of the duct 3a as a unit with the speaker system in the related art causes the following problems.
The related art speaker system can only invert a particular frequency, to require a new rear sound box 2 when it is desired to invert other particular frequency by changing the length or sectional area of the duct 3a, that is impossible as the related art speaker system has unitary duct 3a and sound box 3. And, even if a design of the rear sound box 2 itself is changed for fabricating a new rear sound box 2 in an intention to provide a longer duct 3a, the provision of the longer duct as much as wanted is very difficult since a drawing out angle of a mold should be taken into consideration.
Moreover, the backward exit of the duct 3a from the rear sound box 2 in the related art speaker system causes a sound pressure drop, which weakens a reinforcing power for the sound generated in the front surface.
In summary, the unitary duct 3a and sound box 3 permits no change of the duct only, and the backward exit of the duct 3a from the rear sound box 2 causes a loss of the sound pressure.
Accordingly, the present invention is directed to a speaker system in a display that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a speaker system in a display, in which a duct only can be changed with easy for inverting a phase of a desired frequency, and an inverted sound is made to be discharged to forward for eliminating a sound pressure loss.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the speaker system in a display includes a speaker for presenting a sound, a rear sound box coupled to a back of the speaker, and a changeable duct disposed to pass through a front surface of the speaker and to be positioned in the rear sound box, and detachably fitted to the speaker, for inverting a phase of a particular frequency of sound among sound generated in a back surface of the speaker, and presenting the inverted sound.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.